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Depoisoning process turns used oil into valuable feed

Dec. 8, 1997

Chemical Engineering Partners Inc. (CEP) and Evergreen Holdings Inc. have developed a new recovery process for used oil. Called Sec-Feed, the process turns used oil into a clean, demetallized, noncorrosive paraffin-rich product. According to CEP, the product can be fed back to a nearby refinery as secondary feed for a catalytic cracker, sold as marine diesel, or sold as a low-sulfur blending stock for fuels. Because it removes catalyst poisons, Sec-Feed can also produce secondary feedstocks for

Chemical Engineering Partners Inc. (CEP) and Evergreen Holdings Inc. have developed a new recovery process for used oil.

Called Sec-Feed, the process turns used oil into a clean, demetallized, noncorrosive paraffin-rich product. According to CEP, the product can be fed back to a nearby refinery as secondary feed for a catalytic cracker, sold as marine diesel, or sold as a low-sulfur blending stock for fuels.

Because it removes catalyst poisons, Sec-Feed can also produce secondary feedstocks for existing lube plants.

CEP states that the ability to supply a secondary feed to refineries reduces the refiner's dependence on imported crude oil. Average crude oils have 3-8% lube content, and lube crudes have 12-16% lube content.

By comparison, the recoverable lube content in spent automotive oils is 60-75%. This used oil, if burned or dumped, would mean the loss of a valuable resource as well as a burden on the environment.

Evergreen will build two Sec-Feed plants, one in southern California and another in North Wales at Point of Ayr; both plants are expected to be completed in late 1998.

Sec-Feed process

Fig. 1 [65,249 bytes] shows the Sec-Feed steps to recover high quality lube distillate.

Mohawk pretreatment is a proprietary and patented process which prevents severe fouling, choking, and corrosion of downstream equipment. Dewatering involves flashing the treated oil under near-atmospheric conditions to remove water and light hydrocarbon vapors overhead. Gasoil removal distills the dewatered feedstock under moderate vacuum conditions to extract the fuel fraction from the lubricating oil. The CEP catalyst depoisoning process removes phosphorous and silicon from the lube distillate.

Finally, lube distillate recovery separates the dewatered and defueled feedstock from the heavier hydrocarbons and heavy metal containing additives by evaporating feedstock under very high vacuum conditions in a thin film evaporator. Bottoms from the evaporator leave as asphalt flux. Lube distillate vapors are condensed and sent to storage for use as secondary feeds to refineries.

Table 1 [17,539 bytes] and Table 2 [12,984 bytes] show abridged versions of typical feed and product specifications for the Sec-Feed process.